<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
</head>
<body>
<div id="app">
  <h2 v-if="isShow">{{message}}</h2>  <!-- isShow是一个变量-->
</div>

<script src="../js/vue.js"></script>
<script>
  const app=new Vue({
    el:'#app',
    data:{
      message:'你好',
      isShow:false
    }
  })
</script>
</body>
</html>